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UNITED STATES DEPARTMENT OF AGRICULTURE 
BULLETIN No* 839 

Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 



Washington, D. C. 



April 23, 1920 



THE MICROSCOPICAL EXAMINATION 
OF FLOUR 



By 

GEORGE L. KEENAN, Microanalyst, and 
MARY A. LYONS, Microanalyst, Microchemical Laboratory 



CONTENTS 



Review of Literature 

Purpose of Investigation . . , 
Microscopical Method . . . , 
Sources of Variation in Method , 



Page 
I 
3 
8 
5 



Exmmination of Mill Stoclcs II 



Page 
Examination of Commercial Grades of 

Flour 16 

Examination of Experimental Series of 

Flour 29 

Summary 31 

Biblioeraphy S2 




WASHINGTON 
GOVERNMENT PRINTING OFFICE 

1920 



L^ 



U:\ 



D* or -a 






UNITED STATES DEPARTMENT OF AGRICULTURE 




BULLETIN No. 839 i 

i 



jrL^'^'«-rt. 



Contribution from the Bureau of Chemistry 
CARL L. ALSBERG, Chief 




jru^'^o**^ 



Washington, D. C. 



April 23, 1920 



MICROSCOPICAL EXAMINATION OF FLOUR. 

By George L. Keenan, Microanalyst, and Mary A. Lyons, Microanalyst, 
Microchemical Laboratory. 



CONTENTS. 



Review of literature 1 

Purpose of investigation 3 

Microscopical method 3 

Sources of variation in method 5 

Examination of mill stocks 11 



Examination of commercial grades of flour ... 16 

Examination of experimental series of flour. 29 

Summary 31 

Bibliography 32 



REVIEW OF LITERATURE. 

A review of the literature has shown very few methods for tlie 
microscopical examination of flours. In the great majority of the 
methods found, suggestions are offered for the separation of the 
wheat tissues from the starch material and the subsequent examina- 
tion of the offal under the microscope. The results obtained from 
such microscopical examination, however, are only roughly indicative 
of the offal that may be present. 

The work of Delaye (5)^ was concerned largely with the detection 
of foreign spores in flour and also with the presence of ergot. Girard 
(7) suggested the separation of the gluten from the starch and im- 
purities by forming the flour into a cake and washing it with running 
water. The starch and impurities were separated with a fine sieve, 
and the offal particles examined under the microscope. Kraemer 
dl) has offered a quantitative method for the examination of com- 
mercial flours by means of the microscope, this quantitative method 
to be preceded by a general qualitative examination. A small por- 
tion of the flour was weighed out, a few drops of a reagent added, 
and the number of typical starch grains or characteristic tissues 
enumerated in examining five different portions of the microscop- 
ical mount. Standard samples were employed for purposes of com- 



' The numbers in parenthesis refer to the bibliography on page 32. 
152332°— 20— Bull. 839 1 



2 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

parison. As a rule, not less than 12 microscopical mounts were 
made of the standard and of the sample under examination. 

Kohn (10) weighed out one-half gram of the flour, and added 10 
cubic centimeters of ether, shaking the mixture, to isolate the hairs 
and bran tissues which were subsequently identified under the 
microscope. 

Dedrick (4) placed the flour in question upon a glass, and exam- 
ined it for offal particles, either with the naked eye or by means of a 
powerful magnifier. Particles of bran, germ, or other impurities 
or substances differing from flour were enumerated, five and six 
trials being made and an average struck. In this way he attempted 
to differentiate between the so-called patent, straight, clear, break, 
and low-grade flours. 

Collin (3) considered the microscopical examination of flour quite 
extensively, although he did not take up the question from the stand- 
point of determining the relative amount of offal material present. 
The histology of the wheat grain is fully discussed and illustrated 
with a number of figures. 

Von Liebermann and Andriska (22) suggested a method for esti- 
mating the quality of wheat flour which might possibly be correlated 
with a microscopical examination. The quality of the flour with 
respect to the quantity of bran substance present was ascertamed 
by shaking the flour with chloroform, and observing the color of 
the portion which floated on the surface. The test might be rendered 
quantitative in the following manner: One gram of the flom* was 
shaken in a tube with 10 cubic centimeters of chloroform, and the 
mixture allowed to stand for one hour. The depth of color of the 
layer which then formed on the surface of the chloroform was com- 
pared with the colors of the layers produced when mixtures of finest 
white flours and variable portions of bran were subjected to similar 
treatment. These mixtures might contain quantities of washed bran 
ranging from to 2 per cent. The colors of the layers were to be 
observed from above. 

In connection with the work done by Moore and Wilson (15), Pat- 
terson has made a microscopical examination of the flour streams 
from the different machines of the mill, these streams being blended 
to form various finished fiours. Finished flours were also examined. 
His method consisted in weighuig out 3 milligrams (0.003 gram) of 
flour, dividing this into five portions on as many microscopic slides, 
wetting with water, covering with cover slips, and then counting 
imder the microscope the number of hairs and epicarp and seed- 
coat particles in the five slides. His results tended to show how 
these particles increased in number in streams from the lower-grade 
machines and were practically absent from those from the "top" 
of the mill. 



MICROSCOPICAL EXAMINATION OF FLOUR. 6 

PURPOSE OF INVESTIGATION. 

From the review of the literature, it is apparent that heretofore 
the purpose of the microscopical examination of flour has usually 
been to determine the presence of adulterants, such as other flours, 
or even starches, spores, etc. The paper in which Patterson indi- 
cated the possibilities of an estimation of the offal content of a flour 
microscopically (15) suggested the work here reported. 

MICROSCOPICAL METHOD. 

For convenience, the microscopical method employed in this inves- 
tigation will be described under the following headings: (1) Appa- 
ratus, (2) technique, and ^3) counting bran particles and hairs. 

APPARATUS. 

1. Microscopic slide with a ruled area about 22 millimeters square. 
The lines, which it is convenient to have about h millimeter apart, are 
ruled across the short diameter of the slide. 

2. Cover glasses 22 millimeters square. 

3. Compound microscope, with compensating ocular 12 X and 16 
mm. apochromatic objective. 

4. Scalpel, preparation needles, camel's-hair brush, spatula, alco- 
hol lamp, mechanical stage. 

5. Assay balance. 

6. Chloral hydrate solution about 1:1; preferably not any more 
concentrated. 

TECHNIQUE. 

Before undertaking the examination of a flour microscopically, the 
sample should be thoroughly mixed, and a composite sample with- 
drawn from various parts of the material. A 5-milligram portion of 
flour is carefully weighed out upon accurate balances, and the weighed 
portion transferred to the center of the ruled area on the microscopic 
slide. The scalpel is employed in removing flour from the weigh- 
ing pan to the slide, the small amount which can not be thus re- 
moved being easily brushed onto the slide with the camel's-hair brush. 
The flour being transferred to the slide, about 3 or 4 drops of chloral 
hydrate solution are mixed with the flour by means of the preparation 
needle. Add only enough chloral hydrate solution to fill the space be- 
neath the cover glass. The proper amount is usually about 4 drops 
when a pipette with a 1 -millimeter bore is employed. A pipette of 
larger bore releases too much solution at a time and is less convenient 
to control. It is important that the material be evenly distributed in 
the solution; otherwise flocculation of the flour will occur, rendering 
counting more difficult and less accurate. The square cover glass is 
next applied, and the slide heated over the alcohol flame until the 



4 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

starch grains are dissolved, or the preparation "cleared," as is com- 
monly stated. Vigorous heating of the shde is to be avoided in order 
to prevent burning of the material before the preparation has been 
sufficiently cleared. After gentle heating, the slide is quickly trans- 
ferred to the stage of the microscope, where it is allowed to remain a 
short time before counting is begun. The cold stage causes the larger 
part of the air bubbles that may be present in the preparation to dis- 
appear, the very few that remain not hindering in the enumeration 
of the bran particles and hairs. 

Careful adherence to the details of this technique is necessary to 
insure a suitable slide for counting. If a slide is improperly prepared, 
the resulting count probably wiU not be representative of the flour 
under consideration. 

COUNTING BRAN PARTICLES AND HAIRS. 

A thorough acquaintance with the histology of the wheat grain is 
essential before attempting an examination of flours. An}^ standard 
work on microscopy or plant anatomy of the common food products 
contains adequate descriptions of the tissues of the wheat berry in 
various sections. The following brief description of the anatomy of 
the wheat berry ^ is given for the purpose of indicating the tissues 
which are depended upon for judging a flour with respect to its offal 
content. 

The wheat grain is, botanicaUy, the fruit of various subspecies and 
varieties of the genus Triticum. This grain or fruit consists of a 
series of tissue systems, the outermost of which is the pericarp which 
is composed of three layers, the epicarp, mesocarp, and endocarp. 
The pericarp is essentially the fruit coat or matured ovary wall. 
Within the pericarp is the testa (or spermoderm), rather yellowish- 
brown in color, and easily distinguished in either cross or surface 
sections under the microscope. Within the testa is a layer of rectan- 
gular cells (in transverse section) known as the aleurone layer, contain- 
ing protein material but no starch. This is essentially the outer layer 
of the endosperm or albumen of the seed. The remainder of the grain 
within the aleurone layer consists of very thin-walled parenchymatous 
cells packed full of starch grains. The small embryo, or germ, is 
located at the end opposite the bearded apex. A crease or groove 
passes longitudinally from the base of the grain to the apex. 

The essential purpose of milling is to produce the finely ground 
endosperm or starchy portion of the wheat grain as free as possible 
from bran particles, hairs, and germ tissues. These bran particles, 
hairs, and germ tissues are known as offal in miUing terminology. The 
wheat offal, therefore, consists primarily of all the tissue elements of 

• A. I'. Winton. The Microscopy of Vegetable Foods, 2(1 ed., pp. 65-73. 1916. 



MICROSCOPICAL EXAMINATION OF FLOUR. 5 

the grain from, and including, the aleurone layer outward, and also 
the germ tissues. Botanically, the bran consists of the pericarp, or 
fruit coat, and the aleurone layer. 

In order to discover any relation that might exist between the bran 
particles and hairs and the various so-called gi-ades of flour, the 
microscopical method abeady partially described (page 3) was em- 
ployed to determine the number of bran particles and hairs ordinarily 
found, in varying amounts, in different classes of flours. This enu- 
meration consisted in methodically examining and recording all of the 
bran particles and hairs contaiued in any given slide. It is well to 
form the habit of always starting at the same point in the mount, 
as, for example, the lower right-hand corner of the sHde. The sUde is 
slowly moved by means of the mechanical stage, and aU of the bran 
particles and hairs detected outside the edge of the cover sUp counted. 
Each particle of spermoderm (with accompanying aleurone layer, if 
present), epicarp, cross-cell and intermediate-cell tissues, and hairs 
are given a value of one, no matter how small the particle or hair 
fragment may be, surface as weU as transverse sections being included. 
After the region outside the cover slip is carefully scrutinized, the 
slide is moved over the width of the space between the ruled lines, 
and another strip of the mount examined and the offal* counted. A 
bran particle with hairs attached is counted as so many hairs instead of 
being recorded, for the sake of convention, with the bran particle 
count. Germ tissues were not enumerated. This procedure, as de- 
scribed, is methodically followed until the entire slide has been 
examined. 

SOURCES OF VARIATION IN METHOD. 

In order to study the reliability of the method aside from its practi- 
cal apphcation to the examination of flour, a large niunber of tests 
were made having for their principal purpose the determination of the 
probable sources of variation and their extent. In considering this 
question it was recognized that there might be a variation due to one 
or aU of the following factors: (1) Personal equation, including one 
analyst's variation in counting the same slide on different days and the 
variation between two analysts counting the same slide on the same 
day; (2) daily variation due to the condition of light, etc.; (3) slide 
variation due to limits of accurate weighing of the test portion of 
flour; and (4) the variation in homogeneity of the bulk sample. 

1 For the purpose of this investigation bran particles and hairs were considered as constituting tlie 
offal. 



6 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

PERSONAL EQUATION VARIATION. 
COUNTING THE SAME SLIDES ON DIFFERENT DAYS BY ONE ANALYST. 

Table 1 gives actual data obtained from counts made by each of 
two analysts working upon three slides which were prepared from the 
same bulk sample and upon which they made two counts on each of 
three successive days. 

Table 1. — Results of counts of same slides by two analysts on different days. 



Date. 


SUde. 


Analyst. 


Count 
No. 


Bran 
particles. 


Bairs. 


Total 


1918. 
Jan. 7 


A 
A 
B 
B 
C 

c 

a 
a 

B 
B 
C 
C 
A 
A 
B 
B 
C 
C 
A 
A 
B 
B 
C 
C 
A 
A 
B 
B 
C 
C 
A 
A 
B 
B 
C 
C 


Keenan 


1 
2 
1 
2 

1 
2 
1 
2 
1 
2 
1 

f 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 


87 
92 
60 
60 
87 
81 
103 
114 
86 
80 
90 
87 
76 
82 
60 
49 
62 
64 
100 
% 
85 
77 
89 
83 
80 
83 
49 
53 
60 
77 
104 
100 
78 
77 
86 
86 


59 
64 
60 
58 
62 
74 
58 
52 
64 
58 
62 
57 
66 
69 
55 
48 
60 
68 
54 
56 
52 
55 
65 
59 
65 
66 
61 
57 
66 
71 
54 
55 
55 
55 
65 
62 


146 


Do.. 


do 


156 


Do.. 


do 


120 


Do.. 


do 


118 


Do.. 


....do 


149 


Do.. 


do 


155 


Do.. 


Lyons 


161 


Do.. 


do 


166 


Do.. 


do 


150 


Do.. 


.... do 


138 


Do.. 


do 


152 


Do.. 


do 


144 


Jan. 8 


Keenan 


142 


Do.. 


do 


151 


Do.. 


do 


115 


Do.. 


do 


97 


Do.. 


do 


128 


Do.. 


.. do 


132 


Do.. 


Lyons 


154 


Do 


. . do 


152 


Do.. 


do 


137 


Do.. 


do 


132 


Do 


. do 


154 


Do.. 


do 


142 


Jan. 9 


Keenan . . 


145 


Do.. 


do 


149 


Do.. 


do 


110 


Do. 


do 


110 


Do.. 


do 


126 


Do . 


do 


148 


Do 


Lyons 


158 


Do.. 


do 


161 


Do.. 


do 


133 


Do 


.do... 


132 


Do. 


do 


151 


Do.. 


do 


148 









For the purpose of emphasizing certain salient points, the results 
recorded in Table 1 have been rearranged in Table 2, in considering 
which it is necessary to regard the different portions carefully. 
Keenan's greatest variation in two counts of bran particles on a 
given slide on any one day was 17 points (slide C, Jan. 9, 1918), 
while Lyons' greatest variation was 11 points (slide A, Jan. 7, 1918). 
In the matter of counting hairs the greatest variation in the counts 
obtained on a given slide on any one day by Keenan was 12 points 
(slide C, Jan. 7, 1918), while Lyons' greatest similar variation was 6 
(in several instances). In these cases it appears therefore that the 
personal variation due to the error of counting probably would not 
exceed 17 points in the case of particles or 12 points in the case of 
hairs. 



MICROSCOPICAL EXAMINATION OF FLOUR. 
Table 2. — Variation in counting of each analyst. 



SUde. 


Count 
No. 


Bran particles. 




Hairs. 




Jan. 7, 
1918. 


Jan. 8, 
1918. 


Jan. 9, 
1918. 


Jan. 7, 
1918. 


Jan. 8, 
1918. 


Jan. 9, 
1918. 


A 


Keenan. 
1 
2 
1 
2 
1 
2 

Lyons, 
I 
2 

I 

1 
2 


87 
92 
60 
60 
87 
81 

103 
114 
86 
80 
90 
87 


76 
82 
60 
49 
62 
64 

100 
96 
85 
77 
89 
83 


80 
83 
49 
53 
60 
77 

104 
106 

78 
77 
86 
86 


59 
64 
60 
58 
62 
74 

58 
52 
64 
58 
62 
69 


66 
69 
55 
48 
66 
68 

54 
56 
52 
55 
65 
62 


65 


A 


66 


B 


61 


B 


57 


C 


66 


C . 


71 


A 


54 


A... 


5S 


B 


5i 


B... 


55 


C 


68 


C 


63 







COUNTING THE SAME SUDE ON THE SAME DAY BY TWO ANALYSTS. 

The variation between the counts made by two analysts on the 
same slide on the same day is demonstrated by comparing the daily 
averages * obtained by each of the two analysts. These data are 
compiled in Table 3. 





Table 3. — Varintion in counting of two 


analysts 


on same 


day. 




Date. 


Analyst. 


Bran particles. 


Hairs. 


Slide A. 


Slide B. 


Slide C. 


Slide A. 


Slide B. 


Slide C. 


1918. 


Keenan 


89 
108 
19 
79 
98 
19 
81 
105 
24 


60 
83 
23 
54 
81 
27 
51 
77 
26 


84 
88 
4 
63 
86 
23 
68 
86 
18 


61 
55 
6 
67 
55 
12 
65 
54 
11 


59 
61 

2 
51 
53 

2 

59 
55 

4 


6S 


Jan. 7 


• Lyons 


59 




Variation 


9 




Keenan 


67 


Jan. 8 


■ Lyons 


68 




Variation 


5 




Keenan... 


68 


Jan. 9 


■{Lyons 


61 




Variation 


5 









The table shows an average variation in the comit of bran par- 
ticles of 20, with a range of from 4 to 27. The average variation in 
the count of hairs was 18, with a range of from 2 to 12. It is evident 
that the variation between analysts in making the count of bran 
particles is greater than in making the count on hairs. 

DAILY VARIATION DUE TO CONDITION OF LIGHT. ETC. 

To determine what influence, if any, physical conditions, such as 
degree of light, have upon the count, it is necessary to first eliminate, 
as far as possible, the personal variations already considered. This 
may be accomplished by taking the average of two counts on three 



' By " daily average" is meant the average of two counts made by the same analyst on the same slide 
on a given day. 



8 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



slides for the same day and averaging the three results to determine 
the analyst's daily variation. This is calculated for each analyst. 
The ultimate daily variation is the average of the daily variation of 
the two analysts computed for each day. The daily variation for 
each analyst is shown in Table 4. 

Table 4. — Daily variation for each analyst. 





Variation. 


Bran particles. 


Hairs. 


SUde. 


Jan. 7, 
1918. 


Jan. 8, 
1918. 


Jan. 9, 
1918. 


Jan. 7, 
1918. 


Jan. 8, 
1918. 


Jan. 9, 
1918. 


A 


Keenan. 


89 
60 
84 
77 

108 

83 
88 
93 

85 


79 
54 
63 
65 

98 
81 
86 
88 

76 


81 
51 
68 
66 

105 

77 
86 
86 

76 


61 
59 
68 
62 

55 
61 

59 

58 

60 


67 
51 
67 
61 

55 
53 
62 
56 

63 


65 


B .. 




59 


c 




68 






64 


A . 


Lyons. 


54 


B 




55 


C 




63 




Analyst's daily 


57 




U Itimate daily 


60 













The results in Table 4 seem to indicate that on January 7, 1918, 
there was a tendency to count higher on bran particles than on the 
other days. It is believed, however, that this was in whole or in part 
due to the clearing action of the glycerin employed to preserve the 
slides for counting on subsequent days, which tended to make the 
identification of the bran particles more difficult after the first da}'. 

SLIDE VARIATION DUE TO LIMITS OF ACCURATE WEIGHING OF THE TEST PORTION 

OF FLOUR. 

In order to determine the absolute variation between the slides, 
it is evident that an average must be obtained from which the personal 
variations and the daily variations have been eliminated as far as 
possible. This is accomplished by computing for each slide the aver- 
age of all counts made on bran particles, and also making a similar 
computation for the hair count (Table 5). 

Table 5. — Counts ofhran particles and hairs on slides. 



Bran particles. 


Hairs. 


Slide A. 


Slide B. 


Slide C. 


Slide A. 


Slide B. 


Slide C. 


89 
79 
81 

108 
98 

105 


60 
64 
51 
83 
81 
77 


84 
63 
68 
88 
86 
86 


61 
67 
65 
55 
55 
54 


59 
61 
59 
61 
53 
55 


68 
67 
68 
59 
62 
63 


193 


167 


1 79 


159 


156 


164 



» Average slide count. 



MICROSCOPICAL EXAMINATION OF FLOUR. 



9 



The variation in the counts on these slides naturally raises the ques- 
tion of the limits of accuracy in weighing out the test portion of flour. 
vSince the amount of flour used on a slide is 5 milligrams, it is desirable 
to determine how great is the error due to weighing the test portion of 
flour. The balance employed in this investigation was a fine assay 
balance. In weighing the sample the vibration method was used, 
and the quantity of flour was so adjusted as to produce a deviation 
of approximately not more than one-fourth of a space on each side of 
the zero point of the scale. This is equivalent to not more than 1/40 
milligram, or one-half of 1 per cent, on the basis of the portion of flour 
used (5 milligrams) . Hence any error in weighing can not be accepted 
as an explanation of the difference in slide counts. 

VARIATION IN HOMOGENEITY OF BULK SAMPLE. 

The question has been raised as to whether or not a portion of the 
slide variation might not be accredited to lack of uniformity of the 
bulk sample, due to the fact that any grade of flour is usually the 
component result of several constituent streams which vary more or 
less among themselves. The fact that in general practice the flour 
stocks are subjected to a certain degree of purification, however, 
leaves this factor little chance to figure to any great extent. This 
point was tested by passing a certain sample of flour which had an 
average count of 32 bran particles and 64 hairs through a 30-mesh 
sieve and making up and counting 12 slides. The bulk sample was 
then passed through the sieve once more (making two times for the 
sample), and another series of slides made and counted. Finally, 
the sample was put through the sieve twice more (making four times 
for the sample) , and a third series of 12 slides made and counted. The 
results of these tests are given in Table 6, the counts in which are the 
average of the results obtained by two persons. 

Table 6. — Effect of variation in homogeneity of sample on count. 



Sample passed through 30-mesh sieve- 


Once. 


Twice. 


Four times. 


Bran 
particles. 


Hairs. 


Bran 
particles. 


Hairs. 


Bran 
particles. 


Hairs. 


31 
48 
36 
33 
41 
36 
35 
35 
37 
35 
30 
34 


73 
73 
58 
53 
64 
64 
74 
75 
57 
76 
66 
60 


26 
37 
25 
22 
27 
32 
32 
27 
34 
26 
39 
30 


67 
70 
58 
54 
61 
57 
83 
64 
61 
72 
67 
67 


21 
22 
30 
32 
23 
29 
36 
34 
39 
38 
33 
37 


76 
53 
56 
. 81 
79 
66 
60 
56 
70 
52 
65 
48 


135 

2 18 


166 
2 23 


'29 

217 


165 
2 29 


131 

2 18 


163 

2 31 



152332°— 20- 



1 Average. 
-Bull. 839- 



> Variation 



10 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



Apparently, sifting or thorough mixing of the flour a number of 
times has little appreciable effect upon the offal count obtained. 



NUMBER OF SLIDES COUNTED. 



In practice, two slides, or at most three, from the sample of flour 
have been used as the basis for judgment as to the character of the 
product as far as the offal material was concerned, and the question 
might very properly be asked if that number is sufficient. In order 
to test out this point, 12 slides were prepared from the same bulk 
sample of flour. Two counts on each slide were made of the bran 
particles and hairs by each of two analysts. The results obtained are 
recorded in Table 7. 

Table 7. — Counts on 12 slides. 



Slide des- 
ignation. 


Analyst. 


Count 
No. 


Bran 
parti- 
cles. 


Hairs. 


Slide des- 
ignation. 


Analyst. 


Count 
No. 


Bran 
parti- 
cles. 


Hairs. 


A... 


Keenan 

....do 

Lyons 

. ..do 


1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 


21 

22 
20 
22 
24 
23 
19 
23 
23 
31 
34 
33 
33 
30 
31 
35 
24 
22 
23 
26 
31 
29 
29 
30 


76 
75 

78 
77 
54 
53 
52 
56 
55 
60 
59 
53 
77 
81 
84 
82 
79 
79 
82 
78 
64 
65 
70 
66 


G 


Keenan 

do 


1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 
1 
2 


38 
32 
33 
40 
37 
24 
38 
40 
26 
44 
44 
42 
39 
38 
34 
41 
32 
30 
33 
37 
32 
36 
42 
39 


64 


A 


G 


57 


A... 


G 


Lyons 

do 


61 


A 


G 


61 


B . 


Keenan 

.do 


H 


Keenan 

do 


61 


B 


H 


47 


B 


Lyons 

.do 


H 


Lyons 

do 


56 


B... 


H 


61 


C 


Keenan 

do 




Keenan 

do 


74 


c 




67 


C 


Lyons 

do 


1 1 Lyons 

I ' do 


67 


C 


72 


D 


Keenan 

... do 




Keenan 


50 


D 




do 


55 


D 


Lyons 

do 




Lyons 

do 


48 


D 




56 


E... 


Keenan 

do 


K 


Keenan 

do 


63 


E... . 


K 


60 


Ei 


Lyons 

do 


K 


Lyons 

do 


68 


E... 


K 


71 


F 


Keenan 

.do 


L 


Keenan 

do 


47 


F 


L 


49 


F.. . . 


Lyons 

do 


L Lyons 

L ' do 


47 


F 


51 













From the data in Table 7 it is possible to average Keenan's first 
count on slide A with each count made by him on each of the other 
slides. By averaging the slides by two, 20 is found to bo the lowest 
average and 43 the highest average for bran particles, considering 
Keenan's results only. If the average of counts for three slides 
instead of two is to be taken as the basis for final judgment of the 
product, it is apparent that 22 is the average of the three lowest 
results and 40 the average of the three highest (Keenan's results on 
bran particles). Taking the average of the counts on each of four 
slides gives an average minimum count of 22 and an average maximum 
count of 39. Table 8, based on data obtained from Table 7, has 
been prepared to show the results of such methods of grouping. 



MICROSCOPICAL EXAMINATION' ..i" FI.OUR. 
Table 8. — Effect of method of com,'pvi'>"<t •mv..,,,;,. on count. 



11 



Method of averaging. 



By twos. . 
By threes 
By fours . 
By fives. . 



Bran particles 



Keenan. 



Mln. 



20 


43 


22 


40 


22 


39 


23 


39 



Lyt 



Min. ' Mat. i Miji. 



Hairs. 


Keenan. Lyons. 


iji. 


Max. 


Min. 


Max. 


48 
47 
49 

n 


80 
79 
79 
77 


49 
48 
49 
50 


8.3 
81 

81 
80 



EXAMINATION OF MIL». .>rvM KS. 

Before undertaking a discussion of th*' vv,.rk .Ittue on finished com- 
mercial flours, it seemed advisable to consI'l'T ti.f; degree of purity of 
the various mill stocks entering into li..- ■ ..Mi,.-.sition of the end- 
product. The data compiled in Table '' ■i-in-.n-irate the quality of 
the stocks made on the break rolls, the i>ttri....:, of which is to crush 
the wheat kernel to release the enclosed «(!<l>'Si.r:iQ that is later re- 
duced to fineness on other rolls and firi.t!lv inniiied of offal debris. 
The general practice in milling is to make .iv lii 1 1,> break flour as possi- 
ble. When break flour is made to an\ >. 
tains a notable amount of offal, consist "nv 
as numerous hairs from the beard. Thf- r-' 
were obtained on samples of material pro<ii: 
third, and fourth break rolls, respectively. ;iii(i from different mills. 
It was stated that they had been bolte*' tint. ugh silks of various 
numbers of meshes per lineal inch, thefolU'U in.,' .-irks being employed: 



\i 



f . it invariably con- 
i>r iM-an particles, as weU 
n]\< recorded in Table 9 
• I I'f'vm the first, second, 



Silk number. 


i 

j .W^sl,.:.' 

i 


lOxx !..:• 


llxx ,; 


12xx . 1 ■• 


12x 


12XXX 

13xx 


i l->r. 


14xxx. 







' The designations for the various stocks and grades of flour 6 •..;'.;., ,^1. .> /'ell as the statements concern- 
ing the kind of wheat from which the Hour was milled, weret».l.-en irom t.h« miilers supplying the saniplH.. 
and were not verified in the Bureau of Chemistry. 



12 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 9. — Results of examination of -products from, break machines. 



Sample No. 



Type of wheat. 



Bolting cloth. 



Bran 
particles. 


Hairs. 


196 


165 


186 


83 


117 


43 


334 


162 


76 


61 


46 


64 


113 


38 


182 


58 


324 


42 


166 


65 


216 


162 


105 


23 


150 


83 


47 


44 


32 


54 


142 


58 


75 


38 


138 


31 


120 


121 


628 


107 


367 


144 


159 


26 


118 


53 


68 


60 


37 


56 


375 


73 


131 


53 


135 


46 


810 


213 


322 


116 


262 


57 


118 


50 


132 


147 


228 


106 


285 


66 



Total. 



11079-K-A. 
17146-L-B. 

17125-L-C. 
17128-L-A. 
17159-L-A. 
17173-L-A. 
17165-L-O. 
17167- L-A. 



17143-L-B. 
17146-L-A. 
17190- L-B. 
17125-L-D. 
17128-L-C. 
17159- L-B. 
17173-L-B. 
17133- L-F . 
17165-L-P. 
17167-L-B. 



11079-K-D. 
17143-L-C.. 
17146-L-D. 
17125-L-E. 
17128-L-D.- 
17159-L-C.. 
17173-L-C.. 
17133-L-G. 
17165-L-Q. 
17167-L-C.. 



17143-L-D. 
17146-L-C. 
17125-L-F. 
17128- L-E. 
17173-L-D. 
17165-L-R. 
17167-L-D. 



Hard 

do 

Hard and soft. 

do 

do 

do 

Soft 

do 



Hard 

do 

do 

Hard and soft. 

do 

do 

do 

Soft 

do 

do 



Hard 

do 

do 

Hard and soft. 

do 

do 

do 

Soft 

do 

do 



Hard 

do 

Hard and soft. 

do 

do 

Soft 

do 



FreST BREAK MATEBIAL. 

(?) 

113CX, 13xx 

(?) 

(?) 

(?) 

(?) 

lOxx 

12xxx, 14xxx 

SECOND BREAK MATERIAL. 

lOx, llx 

12xx, 13xx 

12xx, 13xx 

(?) 

(?) ■-• 

(?) 

(?) 

(?) 

lOxx 

12xxx, 14xxx 

THIRD BREAK MATERIAL. 
(?) 

lOx, llx 

12xx, 13xx 

(?) 

(?) 

(?) 

(?) 

(?) 

lOxx 

12XXX, 14xxx 

FOURTH BREAK MATERIAL, 

llx, 12x 

12xx, 13xx 

(?) 

(?) 

(?) 

lOxx 

14xxx 



361 

269 
160 
496 
137 
110 
151 
240 



366 
231 
378 
128 
233 
91 
86 
200 
113 
169 



241 
735 
511 
185 
171 
128 
93 
448 
184 
181 



1,023 
438 
319 
168 
279 
334 
351 



For the purpose of comparison, the data from Table 9 have been 
summarized in Table 10. 



Table 10. — Summary of results of examination of products from break jnachines. 



Machine stock. 


Average. 


Bran 
particles. 


Hairs. 


First break 


156 
139 
213 
308 


84 
60 
73 
122 




Third break 







The offal content of the break roll products is high, as would 
be expected. A microscopical examination is hardly necessary to 
establish this fact. The fluffy and dirty appearance of such products, 
even from casual examination, is sufficient to show that they are of 
low quality, judging from the offal material present. 



MICROSCOPICAL EXAMINATION OF FLOUR. 



13 



Tests similar to those made on break roll products were made 
on middlings stock. Middlings are usually recognized as being the 
medium granular particles of the endosperm resulting from the crack- 
ing of the wheat kernel on the break rolls. After proper purification 
or removal of the branny material, the middlings are milled, on the 
reduction rolls, to the fineness of flour. The results of experimental 
work done on middlings stocks are recorded in Table 11. 

Table 11. — Results of examination of middlings stocks. 



Sample No. 



15196- K-E. 
17144-L-I.. 
17190-L-I.. 
17125-L-L. 
17159-Iv-F . 
17132-L-J.. 
17133-L-L. 
17165- L-B. 
17185-L-C . 



15196- K-C. 
17144-L-J.. 
17146-L-O. 
17190-L-I.. 
17125-L-N. 
17159-L-G. 
17132-L-K. 
17133-L-O. 
17165- L-C . 
17185- L-D. 



17144- L-K. 
17146-L-I.. 
17190-L-J.. 
17125-L-P. 
17128-L-K. 
1715»-L-H. 
17173-L-O. 
17132-L-L. 
17133-L-Q. 
17165- L-D. 
17167-L-J.. 
17185- L-F. 



15196- K-J. 
17190-L-K. 
17125- L^T. 
17128-L-O. 
17159- L-I.. 
17171-L-L. 
17132-L-M. 
17133-L-S. 
17165-L-F . 
17167-L-M. 
17167-L-K. 



15196- K-K. 
17144- L-M., 
17146-L^H.. 
17190-L-L.. 
17128- L-P.. 
17159-I^J... 
17171-L-M.. 
17173-L-P., 
17133-Lr-U.. 
17165- U-H. 
17167- L-O.. 



Type of wheat. 



Hard 

do 

do 

H.ird and soft. 

do 

Soft 

do 

do 

do 



Hard 

do 

....do 

do 

Hard and soft. 

do 

Soft 

....do 

....do 

....do 



Hard 

....do 

....do 

Hard and soft. 

....do 

....do 

....do 

Soft 

do 

do 

do 

do 



Hard 

do 

Hard and soft. 

do 

do 

do 

Soft 

do 

do 

do 

do 



Hard 

do 

....do 

do 

Hard and soft. 

...do 

....do 

do 

Soft 

do 

....do 



Bolting cloth. 



rmST MIDDLIKGS STOCK. 

lOxx, llxx, 12xx 

lOx 

lOxx 

(?) 

(?) 

(?) 

(?) ; 

lOxx 

lOxx 

SECOND MIDDLINGS STOCK 

12xx, 13xx, 14xx 

lOx 

llxx, 12xx 

llxx 

(?) 

(?) 

(?) 

(?) 

lOxx 

lOxx 

THIRD MIDDLINGS STOCK. 

lOx, llx 

llx, 12xx 

lOxx, llxx 

(?) 

(?) 

(?) 

(?) 

(?) 

(?) 

lOxx 

14xxx 

lOxx 

FOURTH MIDDLINGS STOCK 

llxx, 12xx, 14xx 

llxx, 12xx 

(?) 

(?) 

(?) 

llxxx, 12xx 

(?) 

(?) 

12xx 

(?) 

(?) 

FIFTH MIDDLINGS STOCK. 

llxx, 12xx, 14xx 

lOx, llx 

llxx, 12xx 

llxx, 12xx 

(?) 

(?) 

12xx 

(?) 

(?) 

12xx 

(?) 



Bran 
particles. 



5 
7 

29 

100 

11 

7 

25 
59 
48 



10 
76 

7 
38 

8 
82 
26 
36 
29 
115 
40 



Hairs. 



Total. 



10 
31 
150 
12 
12 
26 
65 
75 
12 



10 

101 

8 

61 

18 

01 

27 

31 

31 

139 

4« 



31 
10 
20 
9d 

110 
10 
84 

114 
03 
«T 
53 



14 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 11. — Results of examination of middlings stocks — Continued. 



Sample No. 



15196- K-G... 
17144-L-N... 
17190- L-M... 
17125- L-BB. 
17128- L-Q... 
17173- L-Q... 
17173-I^R... 
17133- L-W.. 
17165-L-I.... 



15196-K-F. 
17144- L-0. 
17190-L-N. 
17128- L-R. 
17159- L-M. 
17133- L-X. 
17165- I^J.. 
17167- L-L. 



17190- L-0. 
17173- L-S.. 
17165-L-K. 



17167-L-S. 



Type of wheat. 



Hard 

do 

....do 

Hard and soft. 

do 

do 

do 

Soft 

do 



Hard 

do 

do 

Hard and soft. 

do 

Soft 

do 

do 



Hard 

Hard and soft. 
Soft 



Soft. 



Bolting cloth. 



SIXTH MIDDLINGS STOCK. 

llxx, 12xx, 13xx, 14xx 

llx, 12x, 13xx 

llxx, 12xx 

(?) 

(?) 

(?) 

(?) 

(?) 

12xx 

SEVENTH MIDDLINGS STOCK 

12xx, 13xx, 14xx 

12x, 13x 

13xx, 14xx 

(?) 

(?) 

(?) 

12xx, 13xx 

(?) 

EIGHTH MIDDLINGS STOCK. 

13xx, 14xx 

(?) 

13xx, 14xx 

NINTH MIDDLINGS STOCK. 
(?) 



Bran 
particles, 



26 
24 

139 
87 
70 
41 
22 

140 
60 



16 

36 
119 

63 
104 
194 
143 

45 



137 

51 

264 



Hairs. 



25 



Total. 



56 
25 
172 
102 
107 
107 
57 
158 



25 

40 
162 

89 
182 
210 
1G« 

58 



160 
103 
302 



117 



The average results obtained on the middhngs stocks examined 
have been summarized in Table 12. 



Table 12. — Summary of results of examination of middlings stocks. 



Stock. 



First middlings.-.. 
Second middlings- 
Third middlings... 
Fourth middlings. 
Fifth middlings... 
Sixth middlings... 
Sevonth middlings 
Eighth middlings.. 
Ninth middlings... 



Average. 



Bran 

particles. 



24 
29 
21 
41 

46 
65 
90 
150 
92 



Hairs. 



Total. 



33 
39 
30 
61 
64 
91 
116 
187 
117 



The results in Table 12 clearly demonstrate that the middhngs 
stocks are much cleaner than stocks obtained from the break rolls. 
The first five middlings stocks average low in the total offal count, 
while the stocks from the sixth to ninth middlings, inclusive, average 
appreciably higher. In other words, the more thorough the purifi- 
cation process, the lower will be the offal count. 

For the purpose of showing the offal count on the stocks which pass 
into some so-called patent flours, three different sets of mill streams 



MICROSCOPICAL EXAMINATION OF FLOUR. 



15 



were examined, these streams being designated as entering into the 
composition of certain finished flours. The mill streams composing 
such flours were milled from hard, blended, and soft wheats, respec- 
tively. The results of these examinations are shown in Tables 13, 
14, and 15. 

Table 13. — Resttlts of examination of mill streams composing a patentflour {sample No. 
171U-L-FF) milled from hard wheat. 



stock. 



Bran 
particles. 


Hairs. 


14 


4 


7 


3 


8 


1 


19 


2 


9 


1 


24 


1 


36 


4 


36 


5 


30 


5 


59 


8 


37 


2 


151 


20 


13 


2 



Total. 



First middlings 

Second middlings 

Third middlings 

Fourth middlings 

Fifth middlings 

Sixth middlings 

Seventh middlings 

Middlings 

Do 

First sizings 

Second sizings 

Sizings 

Finished flour (70 per cent patent)' 



IS 
10 
9 
21 
10 
25 
40 
41 
35 
67 
39 
171 
IS 



> This finished flour Is composed of the stocks described above it. 



Table 14. 



-Results of examination of mill streams composing a patentflour (sample No. 
17159-L--V) milled from blended wheat. 



stock. 



Bran 
particles. 



Hairs. 



Total. 



First break 

Second break 

Third break 

Break chops 

Do 

First middlings 

Second middlings 

Third middlings 

Fourth middlings 

Fifth middlings (head) 

Fifth middlings (tail) 

Coarse tailings 

Coarse sizings 

Finished flour (70 per cent patent) » 



137 
91 

128 
95 

140 
40 
12 
41 
18 
19 
33 
32 
14 
35 



I This finished flour is composed of the stocks described above it. 

Table 15. — Results of examination of mill streams composing a patentflour (sample No. 
ni32-L-U) m,illedfrom soft wheat. 



First middlings 

Second middlings 25 1 26 

Third middlings 9 9 

Fourth middlings 26 1 27 

Fine sizings 10 1 11 

Medium sizings 21 2 23 

Coarse sizings 14 2 16 

Finished flour (60 per cent patent)' 19 1 20 

1 This finished floor is composed of the stocks described above it. 



Bran 




particles. 


Hairs. 


19 


3 


25 


1 


9 





26 


1 


10 


1 


21 


2 


14 


2 


19 


1 



Total. 



<1'6 BULLETIN" 839, U. S. DEPARTMENT OF AGRICULTURE. 

It is interesting to observe the variety of streams drawn upon for 
the composition of different so-called patents, as well as the varia- 
tion in the offal count of the stocks employed in the milling of such 
finished flours. If space permitted, additional information could 
be submitted to illustrate how variable the different mill stocks are 
as far as offal content is concerned. In many instances where 
lower-grade stocks have been employed in making a flour, however, 
the finished product has usually been purified sufficiently to cause 
the resultant offal count to be appreciably low. And in many cases 
the contrary is true. 

EXAMINATION OF COMMERCIAL GRADES OF FLOUR. 

The assembled flours employed in this part of the investigation 
were collected by B. C. Winslow, food and drug inspector. Bureau 
of Chemistry, United States Department of Agriculture. As these 
flours were milled under a variety of conditions, they necessarily 
reflect such conditions in the finished product. The inspector gave 
the following statement as to the designations applied to these 
flours: "As a general thing, these names were used in harmony 
with the usage of the mill where they were taken. The method of 
assembling, with the streams, percentages, etc., were given when 
feasible, and as correctly as possible from the information available. 
The general terms 'patent,' 'clear,' and 'straight' were used to clas- 
sify in a general way the assembled grades of flour, and vary mth 
each mill." 

With this information in mind, an attempt was made to apply the 
microscopical method already described to an examination of these 
products for the purpose of developmg a system for the classification 
of flours based on the offal content. A detailed discussion of the 
actual data obtained from these tests, with a general summary on the 
various so-called grades, follows. 

PATENT FXOURS. 

PATENT FLOURS MILLED FROM HARD WHEATS. 

Thirty-six patent flours said to have been milled from hard wheats 
were examined microscopically, and theij bran particle and hair 
count determined. The commercial grade designations ranged from 
40 to 94 per cent. In some instances the flour had been bleached; 
in others it was bleached only lightly or not at all. Table 16 gives 
the results of this examination. 



MICROSCOPICAL. EXAMINATION OF FLOVR. 17 

Table 16. — Results of examination of patent flours milledfrom hard wheats. 



Sample No. 


Commer- 
cial grade. 


Bleacheu. 


Bran 
particles. 


Hairs. 


Total. 


15163-K-R 


"Per cent 
patent." 
(?) 
(?) 
40 
52 
58J 
60 
65 
68 
68 
70 
70 
70 
71 
72 
72 
74 
74 
75 
75 
75 
75 
75 
77 
78 
79 
80 
80 
80 
83 
83 
83 
84 
85 
85 
88 
94 


Yes 


16 
29 
19 
72 
27 
15 
24 
23 
22 
22 
16 
17 
20 
17 
27 
29 
13 
66 
33 
33 
30 
19 
25 
35 
25 
54 
44 
17 
34 
34 
36 
33 
32 
36 
33 
62 


8 
13 
13 
45 

9 

5 
20 
20 
15 
21 
12 
11 
10 

4 
14 
26 

2 
33 

2 
36 
39 
13 
24 
28 
31 
28 

9 
19 
16 
10 
30 
12 
23 
15 

9 
34 


24 


15178-K-U 


(?) 


42 


17151-L-MM 


No 


32 


17151-L-NN 


No 


117 


17150-L-T 


No 


36 


15152-K-A 


Yes 


20 


15134-K-EE 


No 


44 


11078-K-LL 


No 


43 


11078-K-MM 


Yes 


37 


11070-K-rF 


(?) 


43 


1.5112-K 


No 


28 


15113-K 


Lightlv 


28 


17154-L-AA 


No 


30 


15174-K-LL 


(?) 


21 


15187-K-X 


No 


41 


15170-K-CC 


No 


55 


17144-L-FF 


No 


15 


1719(>-L-CC 


Yes 


99 


17143-L-CC 


No 


35 


15193-K-EE 


No 


69 


15193-K:-DD 


Yes 


69 


11028-K-B 


(?) 


32 


17157-L-A 


Yes . . . 


49 


17183-L-A 


No 


63 


17184-L-Q 


Yes 


56 


11064-K-A 


No 


82 


17175-L-MM 


No 


53 




No 


36 


17147-L-BB 


Yes 


50 


17148-L-MM 


Yes 


44 


17156-L-FF 


Yes 


66 


17155-L-JJ . 


No 


45 


55135-K:-CC 


No 


55 


17145-L-B 


No 


51 


17111-L-S 


No 


42 


17180-L-JJ . 


Yes 


96 









On these hard-wheat patents the bran particle count ranged from 
15 to 72, with an average of 30. The hair count ranged from 2 to 45, 
with an average of 18. The total offal count ranged from 15 to 117, 
with an average of 45. 

PATENT FLOURS MILLED FROM SOFT WHEATS. 

The patent flours milled from soft wheats are more starchy than 
those milled from hard wheats. This starchy character is manifest 
even when the sample of flour is poured out upon a piece of paper. 
The soft-wheat flour will not ''flow" like a flour made from hard 
wheat, but is more "powdery" and starchlike rather than granular, 
as in the case of hard-wheat flours. Thirteen patent flours stated to 
have been milled from soft wheats were examined microscopically. 
As in the case of hard-wheat flours, the commercial grades, as indi- 
cated by percentages, varied markedly, and can be regarded only as 
approximate. The percentages ranged from 35 to 90 per cent. 
Some of the flours were bleached, others lightly bleached, and still 
others not bleached at all. Table 17 gives the results of this examina- 
tion. 



18 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 17. — Results of examination of patent flours milled from soft wheats. 



Sample No. 


Commer- 
cial 
grade. 


Bleached. 


Bran 
particles. 


Hairs. 


TotaL 


17161-L-A 


"Per cent 

patent." 

(?) 

35 

40 

45 

60 

60 

60 

65 

65 

65 

67 

75-80 

90 


Yes 


72 
32 
32 
33 
19 
49 
23 
50 
56 
133 
46 
53 
51 


10 
25 
11 
32 
1 
34 
17 
12 
22 
29 
19 
26 
30 


82 


17189 L 


No 


5T 


17167 L FF 


Yes 


43 


17165-L EE . . 


Yes 


65 


17132 L-U 


No 


2* 


17169 L S 


(?) 


83 


17187- L-V 


No 


40 


15121 K EE 


Yes 


63 


15126 K-FFF 


Yes 


78 


17133 L FF 


Yes 


163 


17161-L-LLL 


No 


65 


17164-L-T. 


(?) 


7» 


11007-K 


(?) 


81 











The bran particle count varied from 19 to 133, the hair count from 
1 to 34, and the total offal count from 20 to 162. The average count 
for bran particles was 49 and that for hairs 20, while the average total 
offal count amounted to 70. 

PATENT FLOURS MILLED FROM BLENDED WHEATS. 

The flours classified under blends were manufactured from mix- 
tures of hard and soft wheats. Similar information was obtained for 
these flours as for the hard and soft types. The designations for 
the so-called grades varied from 70 to 85 per cent. Of the 12 sam- 
ples examined, 4 were bleached and 8 unbleached. Table 18 gives 
the results. 

Table 18. — Results of examination of patent flours milled from blended wheats. 



Sample No. 


Commer- 
cial 
grade. 


Bleached. 


Bran 
particles. 


Hairs. 


Total. 


11084-K 


"Percent 
patent." 
70 
70 
70 
70 
70 
75 
75 
80 
82 
83 
85 
85 


No 


29 
32 
31 
20 
51 
40 
18 
36 
63 
61 
47 
83 


13 
13 
18 
15 
25 
37 
13 
19 
27 
40 
21 
17 


43 


11085-K 


Lightly 


45 


11086 K . . 


Heavily 


4» 


17159- L-V 


No 


;« 


17171-L-B 


No 


78 


17168- L-YS . . ... . 


No 


77 


17168- L-YYH 


No 


31 


17179-I>-YY 


No 

No 

Yes 

Yes 

No 


55 


17127-L-S 


90 


17116-L-D 


101 


17123-L-FF 


68 


17125-L-FF 


100 







The bran particle count ranged from 18 to 83, with an average of 
42. The hair count ranged from 13 to 40, with an average of 21. 
The total offal count ranged from 31 to 101, with an average of 64. 



MICEOSCOPICAL, EXAMINATION OF FLOUR. 



19 



PATENT FLOURS MILLED FROM MIDDLINGS STOCKS ONLY. 

Information was obtained concerning the history of the mill 
streams entering into the composition of a large number of so-caJled 
patent flours. The data collected showed that middlings stocks only 
were employed in composing these flours. The results of the counts 
made on these samples are recorded in Table 19. 

Table 19. — Results of examination of patent flours viilledfrom middlings stocks only. 



Sample No. 



Commer- 
cial 
grade. 



Bleached. 



Bran 
particles. 



Bairs. 



Total. 



17151-L-MM 
15152- K-A.. 
11070- K-PF. 
17154-L-AA . 
17158- L-X... 
15186-K-X.. 
15174-K-LL. 
1S170-K-CC. 
17144-L-FF. 
15181-K-S.. 
15146- K-W. 

15163-K-R.. 



"Per cent 

patent." 

40 

60 

70 

71 

71 

72 

72 

74 

74 

80 

Short 

patent. 

(?) 



Yes 
(?). 
No. 
Yes 
No. 
(?). 
No. 
No. 
Yes 
(?). 

Yes 



Table 19 shows that the bran particle count ranged from 13 to 29, 
with an average of 20, that the hair count ranged from 2 to 26, with 
an average of 13, and that the total offal count ranged from 15 to 55, 
with an average of 33. These results demonstrate the fact that the 
purified middlings stocks employed had some effect upon the purity of 
the end-product. From the information the writers were able to 
obtain, however, so-called patent flours were not always composed of 
the best streams in the mill. 

PATENT FLOURS MILLED FROM MIDDLINGS STOCKS PLUS LOWER-GRADE STOCKS IN THE 

MILL. 

As already stated, stocks other than first-class middlings were often 
passed into patent flours. According to the information submitted, 
break flours and lower grades of middlings frequently were found to 
have been employed in the manufacture of the finished flour. The 
results recorded in Table 20 illustrate the effect of the addition of 
mill streams appreciably high in offal to the finished product. 



20 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

Table 20. — Results of examination of patent flours milled from, middlings stocks in 
addition to lower-grade stocks in the mill. 



Sample No. 


Com- 
mercial 
grade. 


Variety of wheat. 


Bleached. 


Bran 

particles. 


Hairs. 


Total. 


17189-L-O 


'Percent." 

35 
52 
60 
65 
67 
70 
70 
75 
75 
75 
75 
75-80 
78 
79 
80 
80 
82 
83 
83 
83 
84 
85 
85 
85 
94 


Soft 


No 


32 
72 
49 
133 
46 
20 
51 
30 
33 
66 
18 
S3 
35 
25 
54 
36 
63 
34 
36 
61 
33 
47 
83 
32 
62 


25 
45 
34 
29 
19 
15 
25 
39 
36 
33 
13 
26 
28 
31 
28 
19 
27 
16 
30 
40 
12 
21 
17 
23 
34 


57 


17151-L NN 


Hard 


No 


117 


17169-L-S 


Soft 


Yes 


83 


17133- L-FF 


do 


Yes 


162 


17161-L-LLL 


.. . do 


No 


65 


17159- L-V 


Blend. 


No 


35 


17171-L-B 


do 


No 


76 


15193-K-DD 


Hard 


Yes 


69 


15193-K-EE 


do 

. . do 


No 


69 


17190-L-CC 


Yes 


99 


17168-L-YYH... 


Blend 


No 


31 


17164-L-T 


Soft 


Yes 


79 


17183-L-A 


Hard 


No 


63 


17184-L-Q 


do 


No 


56 


11064-K-A 


do 


No 


82 


17179-L-YY 


Blend 


No 


55 


17127-L-S 


.. . do 


Yes 


90 


17147-L-BB 


Hard 


Ye.s 


50 


17156-L-FF 


do 


Yes 


66 


17116-L-D 


Blend 


Yes 


101 


17155-L-,TJ 


Hard 


No 


45 


17123-L-FF 


Blend 


Yes 


63 


17125-L-FF 


. . do 


No 


100 


15135-K-CC 


Hard 


No 


55 


17180- L-JJ. .. 


do 


Yes 


96 











The total offal count on these samples was consistently higher in 
most cases than the results obtained on samples ground from mid- 
dlings stock only. The addition of break flour stocks appeared to 
have a marked effect upon their quality with respect to the offal 
count. The bran particles ranged in count from 18 to 133, with an 
average of 48. The hair count ranged from 12 to 45, with an average 
of 26. The total offal count varied from 31 to 162, with an average 
of 74. 

GENERAL CONCLUSIONS ON PATENT FLOURS. 

1. The commercial grades of so-called patent flours ranged from 
35 to 90 per cent. These percentage figures apparently were in- 
tended to indicate that a certain percentage of the total flour content 
of the wheat kernel passed into this grade, the remainder being 
employed in other grades. 

2. The average total offal count obtained on all commercial patent 
flours examined was 57. 

3. Patent flours showed a marked variation in the total offal comit 
obtained on different samples from various mills. 

4. The limitations and the average counts on bran particles and 
hairs have been briefly summarized in Table 21. 



MICROSCOPICAL EXAMINATION OF FLOUR. 21 

Table 21. — Limitations and average counts on bran particles and hairs for patent flours . 



Commercial grade. 



Bran particles. 



Variation. Average 



Hairs. 



Variation. 



Hard-wheat patent 

Soft- wheat patent 

Blended-wheat patent 



13 to 72. 
19 to 133 
18 to 83. 



2 to 45., 
1 to34., 
13 to 40 



STRAIGHT FLOURS. 

When only one grade of flour is manufactured in the mill, this 
grade is commercially designated as a straight flour, if it contains the 
entire flour content of the wheat that it is possible to mill. It might 
be considered to contain all of the flour that could be obtained from 
the wheat kernel with the exception of a certain percentage of so- 
called low-grade or red dog flour. Such a straight flour naturally 
would contain more of the branny particles from the wheat kernel 
than would a patent flour. The practice of compositing such a flour 
apparently varies in different mills. Tests were made upon a large 
number of straight flours milled from hard, soft, and blended wheats. 
The detailed information on these tests is given in the following para- 
graphs. 

STRAIGHT FLOURS MILLED FROM HARD WHEATS. 

Seventeen straight flours reported as having been milled from 
hard wheats were examined for their offal content. The com- 
mercial grades ranged from 92 to 100 per cent. The results of the 
examination appear in Table 22. 

Table 22. — Results of examination of straight flours milled from hard wheats. 



Sample No. 


Com- 
mercial 
grade. 


Bleached. 


Bran 
particles. 


Hairs. 


Total. 


15196-K-U 


"Per cent 

straight." 

92 

95 

95 

96 

97 

97i 

98 

98 

98 

98 

98 

98 

98 

98 

100 

100 

100 


No 


33 
71 
50 
89 
37 
57 
62 
55 
58 
62 
71 
63 
57 
71 
76 
60 
121 


34 
55 
45 
33 
25 
39 
31 
51 
61 
87 
65 
19 
26 
47 
61 
17 
22 


67 


11028-K-E 


(?) 


126 


17157- L-B 


Yes 


95 


17155-L-HH 


Yes 


122 


15154-K-C . 


Yes 


62 


15106-K 


(?) 


96 


11067-K 


(?) 


93 


15136-K-BB 


Yes 


106 


15147-K 


Yes 


119 


15191-K 


(?) 


149 


15194-K-U 


Ves 


136 


17113-L 


Yes 


82 


17152-L-Y 


(?) 


83 


17177-L-XX . 


No 


118 


11073-K-GG 


(7) 


137 


17146-L-F 


No 


77 


17186-L-F 


No 


143 









The count obtained on bran particles ranged from 33 to 121 and 
that on hairs from 17 to 87. The average bran particle count was 
64 and the average hair count 43. The total offal count ranged 
from 62 to 149, with an average of 106. 



22 BULLETIN 839, U. S. DEPARTMENT OF AGRTCITLTURE- 

STRAIGHT FLOURS MILLED FROM SOFT WHEAT.S. 

Seventeen straight flours reported to have been milled from soft 
wheats were examined. The commercial grades ranged from 90 
to 100 per cent. Table 23 gives the results of this examination. 

Table 23. — Results of examination of straight flours milled from soft wheats. 



Sample No. 


Commer- 
cial 
grade. 


Bleached. 


Bran 
parti- 
cles. 


Hairs. 


Toliil. 


11096-K 


"Per cent 
straight." 
90 
90 
90 
90 
90 
90 

97 
100 
100 
100 
100 
100 
100 
100 
100 


No 


52 
41 
56 
92 
89 
50 
111 
119 
55 
109 
153 
93 
97 
109 
52 
34 
92 


;o 

31 
38 
58 
26 
60 
70 
54 
27 
71 
81 
40 
22 
34 
39 
34 
38 


92 


11097-K... 


Light! v.. . 


72 


11098-K 




94 


15125-K-BB 




150 


15126-K-DJ>D . . 


Yes 


116 


17166- L-Q 


Yes 


110 


15125-K-J"F .... 




181 


15125- K-J.I 


No 


173 


17188-L-X 


No 


82 


15125- K-Y 


Yes 


180 


15125-K-OO .. 


Yes.. 


234 


15126-K-A\A .. . . 


Yes 


133 


17136-L-Z 


Yes 


119 


17165- L-A A 


Yes 


143 


17176-L-W 


No 


91 


17185-L-H 


No 


68 


17186-L-C... . 


No 


130 









The bran particle count varied from 34 to 153, with an average of 
82, and the hair count varied from 22 to 81, with an average of 45. 
The total offal (;ount ranged from 68 to 234, with an average of 127. 

STBAIGHT FLOURS MILLED FROM BLENDED WHEATS. 

Eighteen samples of flour stated to have been milletl from blends 
of hard and soft wheats were examined for their offal content, as in 
the case of the hard and soft types. The commercial grade desig- 
nations varied from 90 to 1 00 per cent. The results of the exam- 
ination are given in Table 24. 

Table 24. — Results of exam.ination of straight flours milled from blended wheats. 



Sample No. 


Commer- 
cial 
grade. 


Bleached. 


Bran 
parti- 
cles. 


Huirs. 


Total. 


11087-K 


"Per cent 
straight." 
90 
90 
90 
90 
90 
90 
90 
90 
96 
97 
97i 
97i 
97* 
97J 
96i 
98 
100 
(?) 


No 


50 
51 
50 
183 
21 
52 
41 
56 
90 
98 
42 
43 
52 
73 
83 
33 
88 
86 


26 
22 
28 
18 
36 
40 
31 
38 
47 
30 
28 
29 
26 
37 
45 
47 
58 
37 


76 


11088-K 


Lightly 


73 


11089-K 


Heavily 


78 


17118-L-J 


No 


201 


17173-L-V 


Yes 


57 


11096-K 


No 


93 


11097-K.... 


Lightly 


72 


11098-K 


Heavily 


94 


17120-L-N 


Yes 


m 


17121-L-SS 

11090-K.... 


No 

No . 


128 
70 


11091-K 


Lightly 


72 


11092-K 


Heavily 

Yes 

No 

No 

No 

No 


78 


17117-Iv-DD 


110 


17115-L-E 


128 


17173-L-W 


80 


15195-K-A 

17128-T,-Z... 


146 

123 







MICROSCOPICAL EXAMINATION OF FLOUK. 



23 



The bran particle count varied from 33 to 183, with an average of 
68, while the hair count varied from 18 to 58, with an average of 34, 
The total offal count varied from 57 to 201, with an average of 100. 
The average total offal count obtained for the straight flours was 111, 
as against 57 for patent flours. 

MILL STREAMS EMPLOYED IN THE MANUFACTURE OF CERTAIN STRAIGHT FLOURS. 

Data were obtained on the mill streams employed in the manu- 
facture of certain straight flours, and these streams were examined 
for their offal content for the purpose of illustrating the quality of 
the material sometimes used in making up such flours. The results 
are given in Tables 25, 26, and 27. 

Table 25. — Results of examination of mill streams employed in the manufacture of a 
straight flour {sample No. 17146-L-F) milled from hard wheats. 



Stock. 



Bran 
particles, 



Hairs. 



Total. 



First break 

Second break 

Third break 

Fourth break 

Fifth break 

Second middlings 

Third middlings 

Third middlings (second stream) 

Fifth middlings 

Cut-off flour 

Cut-off flour 

Chimk flour 

Second chunk flour 

TaiUngs flour 

Tailings flour 

100 per cent straight flour' 



1S6 

166 

367 

322 

456 

29 

27 

13 

21 

15 

76 

308 

50 

76 

155 

60 



83 

65 

144 

116 

176 

2 

6 

4 

5 

4 

18 

90 

5 

24 

47 

17 



269 

231 

511 

438 

632 

31 

33 

17 

26 

19 

94 

398 

55 

100 

202 

77 



' Composited from the mill streams listed above it. 

Table 26. — Results of examination of mill streams employed in the manufacture of a 
straight flour (sample No. 17165-L-AA) milled from soft wheats. 



Stock. 



Bran 
particles. 



Hairs. 



Total. 



First break 

Second break 

Third break 

First, second, and third breaks 

Fourth break 

Fifth break 

First middlings 

Second middlings 

Third middlings 

Fourth middlings 

Fifth middlings 

Sixth middlings 

Seventh middlings 

Eighth middlings 

First germ flour 

100 per cent straight flour ' 



113 

75 

131 

101 

228 

368 

21 

48 

26 

29 

55 

60 

143 

264 

50 

109 



38 
38 
53 
45 
106 
173 

8 
27 

7 

2 
12 
18 
23 
38 

5 
34 



151 
113 

184 

146 

334 

641 

29 

75 

33 

31 

67 

78 

166 

302 

55 

143 



' Composited from the mill streams listed above it. 



24 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



Table 27. — Results of examination of mill streams employed in the manufacture of a 
straight flour {sample No. 17128-L-Z) milled from blended wheats . 



stock. 



First break 

Second break 

Third break 

Fourth break 

Fifth break 

First middlings 

Second middlings.. 
Third middlings. . . 
Fourth middlings. . 

Fifth middlings 

Sixth middlings . . . 
Seventh middlings. 

First sizings 

Second sizings 

First tailings 

Second tailings 

Head cuts 

Tailcuts 

Straight flour 1 



Bran 
particles. 



Hairs. 



334 

150 

118 

118 

296 

66 

41 

69 

38 

74 

70 

63 

56 

107 

134 

108 

132 

130 

87 



162 
83 
53 
50 

101 
31 
21 
26 
23 
36 
37 
26 
11 
34 
43 
48 
63 
70 
37 



Total. 



496 

233 

171 

168 

397 

97 

62 

95 

61 

110 

107 

89 

67 

141 

177 

156 

195 

200 

124 



1 Composited from the mill streams listed above it. 
GENERAL CONCLUSIONS ON STRAIGHT FLOUES. 

1. The commercial grades of so-called straight flours ranged from 
90 to 100 per cent. 

2. The average total offal count obtained on all commercial straight 
flours examined was 111. 

3. Straight flours showed a decided variation in the total offal 
count obtained on different samples from various mills. 

CLEAR FLOURS, 

Clear flour, so-called, is often considered among millers as being a 
mixture of odds and ends of the milling stocks. Low grades of mid- 
dlings and break flours often pass into it, although frequently it con- 
tains the purest quality of middlings stock from the tail of the mill. 
Clear flours which were said to have been milled from hard, soft, and 
blended wheats, respectively, were examined. 



CLEAR FLOURS MILLED FROM HARD WHEATS. 

Thirty-one clear flours stated to have been milled from hard wheats 
were examined. Their percentages ranged from 6 to 52. Table 28 
shows the counts thus obtained. 



MICROSCOPICAL EXAMINATION OF FLOUR. 25 

Table 28. — Results of examination of dear flours milled from hard wheats. 



Sample No. 




Bleached. 



Bran 
particles. 


Hairs. 


331 


132 


238 


166 


306 


50 


191 


98 


197 


77 


156 


126 


294 


223 


181 


102 


271 


184 


241 


62 


193 


136 


127 


119 


65 


39 


82 


68 


71 


67 


131 


124 


410 


196 


172 


140 


193 


204 


158 


102 


316 


71 


271 


93 


92 


71 


79 


57 


77 


49 


127 


178 


268 


43 


118 


133 


126 


114 


151 


147 


72 


45 



Total. 



17180-L-KK. 
17151-L-OO. 
17142-L-EE. 
17112- L-T... 
17150-L-U. . . 
15138-K-DD. 
17154-L-CC.. 
17145-L-A... 
17147-L-AA . 
17175-L-NN. 
17183-L-B... 
17184-L-P... 
11065-K-A... 
11079-K-JJ.. 
11079-K-KK 
15169-K-DD. 
15192-K-FF . 
15186- K-Y . . 
n028-K-C... 
15175-K-MM 
17143-L-BB. 
17144- L-II... 

15115-K 

15n6-K 

15117-K 

11071-K-EE. 
17186-L-E... 
15150-K-AA. 
15137- K-FF. 
15180- K-A A. 
17151-L-NN. 



'Per cent 
clear." 
6 
8 
10 
12 
12 
13 
14 
15 
15 
15 
16 
16 
18 
22 
22 
23 
23 
24 
25 
25 
25 
26 
27i 
27i 
27J 
30 
30 
35 
33-35 
18 
52 



Yes 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

No 

(?) 

No 

Yes 

(?) 

Yes.... 

No 

(?) 

(?) 

No 

No 

No 

Lightly- 
Heavily 

(?) 

No 

Yes.... 

(?) 

(?) 

No 



463 
404 
356 
289 
274 
282 
517 
283 
455 
303 
329 
246 
104 
150 
138 
255 
606 
312 
397 
260 
387 
364 
163 
136 
126 
305 
311 
251 
240 
298 
117 



The bran particle count on these samples varied from 65 to 331, 
with an average of 174. The hair count ranged from 43 to 223, with 
an average of 109. The total offal count varied from 104 to 517, 
with an average of 295. 

CLEAR FLOURS MILLED FROM SOFT WHEATS. 

Thirteen samples of clear flour reported to have been milled from 
soft wheats were examined, these samples varying from 5^ to 50 
per cent as far as commercial grades are concerned. Table 29 gives 
the results obtained. 

Table 29. — Results of examination of clear flours milled from soft wheats. 



Sample No. 


Com- 
mercial 
grade. 


Bleached. 


Bran 

particles. 


Hairs. 


Total. 


15122-K-AA 


"Per cent 
clear." 
5| 
5i 
5i 
20 
25 
30 
30 
30 
30 
35 
50 
50 
25 




243 
244 
282 
137 
308 
245 
208 
235 
160 
247 
126 
177 
253 


155 
164 
99 
66 
30 
167 
143 
44 
40 
39 
32 
68 
72 


• 398 


15122- K-LL. . 


No 


408 


15126- K-EEE 


(?) 


381 


17178-L-AAS... 


No 


203 


17132-L-W 


No 


338 


15122- K-DD 


Yes 


412 


15122- K-MM 


No 


351 


17160- L-D 


Yes 


279 


17162-L-U. . . 


No 


200 


17133-L-EE.. 


Yes 


286 


17167- L-GG... 


Yes 


158 


171S6-L-B. 


No 


245 


11006-K 


(?).. 


325 









26 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



The bran particle count varied from 126 to 308, with an average 
of 218. The hair count ranged from 30 to 167, with an average of 
86. The total offal count ranged from 158 to 412, with an average 
of 306. 

CLEAR FLOURS MILLED FROM BLENDED WHEATS. 

Twelve samples of flour stated to have been milled from blended 
wheats were examined. The commercial grades ranged from 10 to 
30 per cent. Table 30 gives the results of the examination. 

Table 30. — Results of examination of clear jiours milled from blended wheats . 



.Sample No. 



Com- 
mercial 



Bleached. 



Bran 
particles. 


Hairs. 


115 


61 


127 


65 


250 


73 


297 


40 


209 


96 


76 


45 


55 


49 


61 


47 


166 


142 


112 


98 


88 


44 


111 


67 



Total. 



17179-L-ZZ. 
17116-L-E.. 
17123-L-GG 
17125-L-GG 
17171-L-C . . 

11093-K 

11094-K.... 
11095-K . . - . 
17182-L-II.. 
17173-L-Y. . 
17172-L-BB 
17159-L-W. 



"Per cent 
clear. " 
10 
15 
15 
15 
20 
27i 
27i 
27i 
30 
40 
60 
25 



No 

No 

No 

No 

No 

No 

Lightly 
Heavily 

No 

No 

Yes.... 
No 



176 
192 
323 
337 
305 
121 
104 
108 
308 
210 
132 
178 



The bran particle count varied from 55 to 297, with an average 
count of 139, and the hair count varied from 40 to 142, with an 
average of 69. The total offal count varied from 104 to 337, with 
an average of 207. 

mill streams employed in THE MANUFACTURE OF CERTAIN CLEAR FLOURS. 

Tables 31 and 32 record the results obtained on certain mill 
streams which were employed in making up clear flours. As in the 
case of the commercial grades already considered, these figures are 
merely submitted to demonstrate the quality of the stocks that might 
be used in such a flour from the standpoint of offal material. 

Table 31. — Results of examination of will streams employed in the manufacture of a 
clear flour (sample No. ni4S-L-BB) milled from hard wheat. 



Stock. 



First and third breaks. 

Second break 

Third break 

Fourth break 

First tailings 

Second tailings 

Third tailings 

Fourth tailings 

First germ flour 

Second germ flour 

First dustings flour.... 
Third dustings flour... 
Dust collector material 
25 per cent clear flour » 



Bran 
particles. 


Hairs. 


310 


69 


324 


42 


628 


107 


810 


213 


120 


5 


120 


4 


38 


1 


667 


72 


430 


38 


560 


33 


184 


28 


110 


15 


575 


99 


316 


71 



Total. 



360 
366 
735 
1,023 
125 
124 
3» 
639 
46» 
59S 
21t 
12S 
674 
38T 



1 Composited from the mill streams listed above it. 



MICROSCOPICAL EXAMINATION OF FLOUR. 



27 



Table 32. — Results of examination of mill streams employed in the mamifacture of a 
clear flour (sample No. 11079-K-JJ) milled from hard wheat. 



Stock. 



First break 

Third break (head) , 

Third break (tail) , 

Fifth middlings , 

SLxth middlings (head) 

Sixth middlings (tail) 

Seventh middlings (head) . 

First siziags 

First tailings (head) , 

First tailings (tail) 

22 per cent clear flour ' 



Bran 
particles. 


Hairs. 


Total. 


196 


165 


361 


120 


121 


241 


100 


103 


203 


28 


24 


52 


46 


45 


91 


55 


26 


81 


56 


27 


83 


87 


31 


118 


151 


58 


209 


87 


32 


119 


82 


68 


150 



1 Composited from the mill streams listed above it. 

GENERAL CONCLUSIONS ON CLEAR FLOURS. 

1. The commercial grades of so-called clear flours ranged from 5^ 
to 52 per cent. 

2. The average total offal count obtained on all commercial clear 
flours examined was 273. This amount was decidedly in excess of 
the amount obtained on the commercial grades already considered. 

3. As in the case of the other grades, clear flours showed a wide 
variation in the total offal count obtained on products from different 
mills. 

LOW-GRADE FLOURS. 

The low-grade flour is supposed to be made from low-grade mill 
stocks, as might be inferred from the designation applied to this 
class of products. As already stated, the better stocks, for the most 
part, are diverted into the higher grades. The streams entering 
into the composition of the low-grade flours are usually more or less 
specky, due to the presence of offal material. For this reason it is 
quite impossible to obtain an accurate count on such a flour. In 
fact, a casual microscopical examination is usually all that is neces- 
sary to determine the quality of the flour. 

LOW-GRADE FLOURS MILLED FROM HARD WHEATS. 

Eleven low-grade flours milled from hard wheats were examined, 
with the results shown in Table 33. The commercial grades ranged 
from 2 to 10 per cent, some of the samples being bleached and others 
unbleached. 

Table "i'i.^-Results of examination of low-grade flours milled from hard wheats. 



Sample No. 


Commer- 
cial grade. 


Bleached. 


Bran 
particles. 


Hairs. 


TotaL 


11066-K 


"Per cent 

low- 
grade." 
2 
2i 
2i 
2§ 
3 
2-5 
5 
5 
8 
6 
10 


(?) 


243 
310 
340 
310 
252 
175 
353 
274 
269 
169 
317 


91 
129 
131 
112 
155 

88 
301 
335 
264 
163 
238 


334 


15118-K 


No 


439 


15119 K 


Lightly 


471 


15120-K 


Yes 


422 


a5156-K D 


No 


407 


15148- K-X 


No 


263 


11080-K HH 


No 


654 


1108()-K-II 


Yes 


609 


•11029-K D 


(?) 


533 


11072 K OO 


(?) 


332 


11080- K-OO 


Yes 


555 












28 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



The bran particle count varied from 169 to 353, witli an average 
of 273. The hair count ranged from 88 to 335, with an average of 
182. The total offal count varied from 263 to 654, with an average 
of 456. 

LOW-GRADE FLOURS MILLED FROM SOFT WHEATS. 

The eight samples of low-grade flour milled from soft wheats ranged 
from 2 to 10 per cent, with bleaching being practiced in some instances 
and not in others. Table 34 gives the results of this examination. 

Table 34. — Results of examination of loiv-grade flours milled from soft vheatf!. 



Sample No. 


Commer- 
cial grade. 


Bleached. 


Bran par- 
ticles. 


Hairs. 


Total. 


17136-L-Y 


"Percent 
low- 
grade." 

■ (?) 

(?) 

2 

3 

4i 

I' 
10 


(?) 


202 
113 
309 
238 
402 
390 
307 
331 


27 
257 
1:5 
261 
219 
139 
124 

80 


229 


17185-L-G 


No 


409 


17176-L-X 


No 


454 


17188-L-W 


No 


499 


15123-K Z . 


Yes 


621 


15126-K-CCC 


No 


529 


17178-L-BBS 


No 


I.'?! 


1716&-L-Y 


Yes 


411 









The bran particle count varied from 143 to 402, with an average 
of 302. The hair count ranged from 27 to 261, with an average of 
140. The total offal count varied from 229 to 621, with an average of 
446. 

LOW-GRADE FLOURS MILLED FROM BLENDED WHEATS. 

Eight samples of flour stated to liave been milled from blended 
wheats ranged in commercial grades from 1^ to 10 per cent, only one 
sample of the number being represented as having been bleached. 
The results of the examination are shown in Table 35. 

Table 35. — Results of exam,ination of low-grade flours milled from blended wheats. 



Sample No. 


Commer- 
cial grade. 


Bleached. 


Bran par- 
ticles. 


Hairs. 


Total. 


17123 L EE 


"Percent 

low- 
grade." 
(?) 
(?) 
li 
3i 
4 
5 

10 
10 


No 


394 
100 
211 
357 
397 
237 
281 
262 


59 
61 
76 
141 
183 
94 
131 
132 


45.1 


17128-L-T 


No 


161 


17117-L Y 


No 


287 


17115- L-F 


(?) 


498 


17120- L-J 


No 


580 


17171- L-D 


No 


331 


17172- L-AA. . 


Yes 


412 


17179-I>-AAA 


No... . . 


394 









The bran particle count had limitations of from 100 to 397, with 
an average of 279. The hair count varied from 59 to 183, with an 
average of 109. The total offal count ranged from 161 to 580. with 
an avcrajjo count of 389. 



MICROSCOPICAL EXAMINATION OF FLOUR. 



29 



GENERAL CONCLUSIONS ON LOW-GRADE FLOURS. 

1 . The commercial grades of so-called low-grade flours ranged from 
2 to 10 per cent. 

2. The average total offal count obtained on all commercial low- 
grade flours examined was 433. This indicated that not as much 
attention was given to the purification of the stocks passing into 
such flours as was done in the case of the stocks composing the 
grades already considered. 

3. The data obtained on the low-grade flours milled from the dif- 
ferent wheats are summarized in Table 36. 



Table 36. — Limitations and average counts on bran particles and hairs for low-grade 

flours. 





Type. 


Bran particles. 


Hairs. 




Variation. 


Average. 


Variation. 


Average. 


Hard wheat 


169 to 353.... 
143 to 402.... 
100 to 397.... 


273 
302 
279 


88 to 335 

27 to 261 

59 to 183 


182 


Soft wheat 


140 




109 







EXAMINATION OF EXPERIMENTAL SERIES OF FLOUR. 

In connection with the examination of commercial flours it was 
considered advisable to examine samples of flour whose composition 
was definitely known, as far as the wheat from which they were milled 
and their constituent streams were concerned. The information in 
regard to the commercial samples was definite enough in so far as 
the milling operator was able to judge. 

The samples of flour employed in tliis part of the investigation were 
milled under the personal supervision of B. C. Winslow, food and 
drug inspector, Bureau of Chemistry, United States Department of 
Agriculture. The samples were prepared at a plant at Lyons, Kans., 
a portion being milled from a No. 2 Nebraska hard winter wheat, crop 
of 1914, containing from 25 to 35 per cent of yellow berry wheat, and 
another portion from a Kansas No. 2 hard winter wheat. Each type 
of flour was subjected to three degrees of bleacliing, thus making 
three samples for each type. Four types of flour were made from 
each wheat, a 70 per cent, a 90 per cent, a 97.5 per cent, and a 27.5 
per cent. In the case of the Kansas wheat a fifth type, a 2.5 per cent, 
was made. The component streams that passed into each type and 
the results of the examinations made were as follows: 

THE 70 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 

First sizings floior. Fourth middlings flour. 

Second sizings flour. Fifth middlings flour. 

First middlings flour. Fine tailings flour. 

Second middlings flour. Coarse tailings flour. 
Third middlings flour. 



30 



BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 



Table 37. — Results of examination of 70 per cent type of experimental flour. 



WTieat. 


Sample number. 


Decree of 
bleaching. 


Bran 
particles. 


Hairs. 


Total. 




111084-K 


None 


29 
32 
31 
10 
12 


13 
13 
18 
12 
9 
0) 


42 




•IllOSS-K 


Lightly 


45 




I1IO86-K 


Heavily 


49 




(15112-K 


None 


22 




•{15113-K 


Lightly 


21 




(15114-K 


Heavily 


(') 








Average count 


22 


13 


35 











1 Not counted; infested with weevils. 
THE 90 PER CE>rr TYPE OF EXPERIMENTAL FLOUR. 



COMPOSITION. 



First sizings flour. 
Second sizings flour. 
First middlings flour. 
Second middlings flour. 
Third middlings flour. 
Fourth middlings flour. 
Fifth middlings flour. 
Fine tailings flour. 
Coarse tailings flour. 



Second break flour. 
Third break flovir. 
Fourth break flour. 
Sharp section (middlings). 
Cut-off flour (middlings). 
Sixth middlings flour. 
Seventh middlinofs flour. 
Eighth middlings flour. 



Table 38. — Results of examination of 90 per cent type experimental flour: 



Wheat. 


Sample number. 


Degree of 
bleaching. 


Bran 
particles . 


Hairs. ; Total. 

1 




(11087-K 


None 


50 
51 
50 
32 
31 
28 


26 76 




hl088-K 


Lightly 


22 7J 




Ill089-K 


Heavily 


28 78 




nol09-K 


None 


31 0» 




hsilO-K 


Lightlv . . 


28 
34 


59 




[iSlll-K 


Heavily 


62 












40 


28 


6« 











THE 97.5 PER CENT TYPE OF EXPERIMENTAL FLOUR. 



COMPOSITION. 



First sizings flour. 
Second sizings flour. 
First middlings flour. 
Second middlings flour. 
Third middlings flour. 
Fourth break flour. 
Sharp section (middlings) 
Cut-oft flour (middlings). 
Sixth middlings flour. 
Seventh middlings flour. 



Fourth middlings flour. 
Fifth middlings flour. 
Fine tailings flour. 
Coarse tailings flour. 
Second break flour. 
Third break flour. 
Eighth middlings flour. 
First break flour. 
Fifth break flour. 



Ninth middlings flour. 
Flour from dust-collecting reels. 

Table 3d.— Results of examination of 97.5 per cent type of experimental flour. 



Wheat. 


Sample number. 


Degree of 
bleaching. 


Bran 
particles. 


Hairs. 


Total. 




fll090-K 


None 


43 

43 
52 
57 
43 
28 


28 
29 
26 
39 
29 
30 


70 




11091-K 


Lightlv 


72 




11092-K 


Heavily 


78 


No. 2 Nebraska, hard winter. 


1510&-K 


None 


9ft 




15107-K 


Lightly 


78 




15108-K 


Heavily 


58 












44 


30 


74 











MICROSCOPICAL examinatio:n" of flour. 



31 



THE 27.5 PER CENT TYPE OP EXPERIMENTAL FLOUR. 



Second break flour. 
Third break flour. 
Fourth break flour. 
Sharp section . 



COMPOSITION. 

Cut-off flour (middlings). 
Sixth middlings flour. 
Eighth middlings flour. 
First break flour. 



Fifth break flour. 
Ninth break flour. 
Flour from dust collectors. 
Seventh middlings flour. 



Table 40. — Results of examination of 27.5 per cent type of experimental flour. 



Wheat. 


Sample number. 


Degree of 
bleaching. 


Bran 
particles. 


Hairs. 


Total. 




fll093-K 


None 


76 
55 
61 
56 
49 
51 


45 
49 
47 
65 
51 
40 


121 




•{11094-K 


Lightly 


104 




Ill095-K 


Heavily 


108 




(15115-K 


None..'. 


121 


No 2 Kansas, hard winter.. 


h5116-K 


Lightly 


100 




[l5117-K 


Heavily 


91 










Average 


58 


49 


107 











THE 2.5 PER CENT TYPE OF EXPERIMENTAL FLOUR. 

COMPOSITION. 

Bran duster flour. Shorts duster flour. 

Cut-off flour from seventh middlings. Cut-off flour from ninth middlings. 

Table 41. — Results of examination of 2.5 per cent type of experimental flour . 



Wheat. 


Sample number. 


Degree of 
bleaching. 


Bran 
particles. 


Hairs. 


Total. 




(15118-K 


None 


310 
340 
310 


129 
131 
112 


439 


No. 2 Kansas, hard winter... 


•{15119-K 


Lightly. . . . 


471 




Il5120-K 


Heavily 


422 










Average 


320 


124 


444 











GENERAL CONCLUSIONS ON EXPERIMENTAL TYPES OF FLOUR. 

The best grade of flour of the experimental series averages a lit- 
tle lower in total offal count than the best grade in the commercial 
set, being 57 for the commercial flours and 35 for those of the experi- 
mental set. The two intermediate grades of the commercial flours 
were higher in the offal count than similar grades in the experimental 
series, the count being 111 and 273 for the commercial flours and 71 
and 107 for those of the experimental set. Both of the lower- grade 
flours, that from the commercial and experimental sets, respectively, 
compared very favorably as far as the offal count was concerned, 
these figures being essentially minimum ones although approxi- 
mately representative of the two products. 

SUMMARY. 

1. Microscopical technique was devised for the enumeration of 
the offal material in flour of various conmiercial grades. 

2. The data obtained on the various commercial grades of flour 
demonstrated that there was little uniformity in the matter of grad- 
ing finished flours in different mills. 

3. The experimental data submitted have shown a wide range in 
the offal content among flours of the same commercial grade (appar- 
ently) produced by different mills. 

4. The information obtained concerning the samples examined 
leads to the inference that all mills do not composite finished flours 
in the same manner. 



32 BULLETIN 839, U. S. DEPARTMENT OF AGRICULTURE. 

5. The microscopical examination of the constituent streams en- 
tering into the composition of a finished flour shows the effect of the 
addition of different mill stocks on the resulting offal content. 

BIBLIOGRAPHY. 

(1) Amos, P. A. 

Processes of Flour Manufacture. 1912. 

(2) Bellier, J. 

Recherche microscopique des farines eirangeres dans la farine de bl6, partic- 
ulierment du riz et de la feverolle. Ann. chim. anal., J^:224-228. 1907. 

(3) Collin, Eugene. 

Recherche de la farine de riz dans la farine de h\^. Ann. chim. anal., i./:446- 
453. 1906. 

(4) Dedrick, B. W. 

Establish Definite Grades of Flour, Offal, and Stock. The Operative Miller, 
18:441, 467. 1913. 

(5) Delate, L. 

Etude sur I'analyse et I'examen microscopique des farines. Rev. intern, fals., 
6:173-175, 188-190. 1893. 

(6) Gastine, J. 

Nouveau proc6d6 d'analvse microscopique des farines et recherche du riz dana 
les farines de hU. Ann. chim. anal., 17:281-283. 1906. 

(7) GiRARD, Aime. 

L' Appreciation des farines. La Meunerie Francaise, 12:8-10. 1896. 

(8) Hanausek, T. F. 

Ueber unser Mehl und Brot von botanischen Gesichtspunkten betrachtet. 
Wiener illustrirte Garten-Zeitung, ;g^:109-118. April, 1899. 

(9) Huss, Harald. 

Uber die quantitative Bestimmung von vegetabilischen Pulvern mit dem 
Mikroskop. Landw. Vers. Sta., 60:1-13. 1904. 

(10) KoHN, Eduard. 

Beitrage zur Mehluntersuchung. Chem. Ztg., 56:121-123. 1912. 

(11) Kraemer, H. 

An Examination of Commercial Flour. J. Am. Chem. Soc, fi:650-663. 1899. 

(12) Lanoe, Dr. 

Beitrage zur mikroskop. Untersuchung von Mehlproben. Z. angew. Mik- 
roskopie, :?:369-370. 1896. 

(13) Leandre, M. 

Methodes pratiques d'analvses des farines. Rev. intern, fals., 6:133-136, 
153-156. 1893. 

(14) Marcille, R. 

Analyse microscopique des farines. Ann. chim. anal., ii:371-372. 1906. 

(15) Moore, B., and Wilson, J. T. 

The Effects of Nitrogen Peroxide on the Constituents of Flour in Relation to 
the Commercial Practice of Bleaching Flour with that Reagent. J. Hyg., 
15:438^66. Jan., 1914. 

(16) POSNER, C. 

Studien zur Mikroskopie von Mehl und Brot. Zeit. Nahr. Genussm., ^9:329- 
337. 1915. 

(17) Rammstedt, Otto. 

Die Bestimmung der Farbe des Mehles und das Sichtbarmachen von Klei- 
teilchen in Mehl und Griesz. Pharm. Zentralhalle, 56:291-293. 1915. 

(18) Savini, G., and Silvestri, G. 

Estimation of the Quality of Flour. Ann. Lab. chim. cent. Gabelle., 6:425- 
433. 1912. (Abstract in Analyst, 5,^:55-56. 1913.) 

(19) SCHAFFNIT, E. 

Zu Mehluntersuchung. Zeit. Nahr. Genussm., 77:86-88. 1909. 

(20) Snydek, H. 

The Analysis of WTieat Flour for Commercial Purposes. 
V. Intemationaler Kongress fiir AngewandteChemie, Section VI, pp. 702-710. 
Berlin, 1904. 

(21) Testoni, G. 

Micro.scopic Analysis of Flour and Bread. Staz. sper. agrar. ital., -^cS": 143-150. 
1915. (Abstract in Chem. Abstracts, ,9:2951.) 

(22) von LiEBERMANN, L., and Andriska, V. 

Ein neues v'erfahren zur Bestimmung des Feinheitsgrades der Weizeninehle. 
Zeit. Nahr. Genussm., 22:2%1-2M. 1911. 

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